(1) Field of the Invention
This invention relates in general to a banding tool for drawing and securing a metal band or strap tightly around an object such as, for example, the fiberglass or asbestos layer insulation commonly provided around pipelines, towers, vessels, tanks, and the like.
(2) Description of the Prior Art
It is common practice to provide an outer cover layer of fiberglass, asbestos, or other such blanket type insulation on various industrial and commercial pipelines, towers, vessels, tanks and the like, as for example, those employed in petrochemical and power generating facilities. For weather protection as well as appearance considerations, the blanket insulation is generally covered with a thin metal jacket layer of either aluminum, galvanized iron, or stainless steel. The blanket insulation, either with or without the protective outer metal jacket layer, is held tight in place around the pipeline or other vessel by means of a series of spaced metal bands or straps of aluminum, galvanized iron, or stainless steel. These bands are drawn tight around the insulation or metal jacketing and each locked in place in such tensioned state by a metal locking or fastening clip commonly referred to in the art as a wing seal and comprised of a shallow box-shaped section with a pair of upstanding locking lugs at one end.
In the application of the metal retaining bands around the layer insulation or its protective metal jacket layer where employed, each band is first secured at one end to its fastening clip by passage of the band end through the box-section of the clip from the end thereof opposite the locking lugs thereon and bending the inserted band end back tight around the bottom wall of the clip box-section. The band, together with its attached clip on one end, is then positioned or strung around the circumference of the insulation covered pipeline or other vessel and its other or free end passed through the box-section body portion of the fastening clip following which the band is then drawn or pulled tight around the pipeline or other vessel, by pulling forces applied to its opposite ends, and the free end of the band while thus tensioned then bent back over the top wall of the clip body section to secure the band in place in its tightened condition around the pipeline. After trimming off the excess length of the bent back free end of the band at a point a short distance beyond the locking lugs of the clip, the lugs are then bent down over the trimmed bent back free end of the band to lock it securely in place in the clip against any unwanted loosening therefrom, thus completing the band-applying operation.
The above described drawing or pulling of the metal band tight around the layer insulation or its protective metal jacketing on the pipeline or other vessel, and the bending back of the free end of the band over the top wall of the fastening clip, is customarily performed by the band applying workman with the use of a so-called banding tool. While various types of such banding tools have been heretofore available for the purpose, they have all possessed certain disadvantages such as their being of bulky and heavy form, expensive, and cumbersome and difficult to operate. Many of these tools are designed for use primarily by right-handed operators and thus are difficult to use by left-handed operators. Also, the most commonly used tools employed heretofore have generally incorporated a ratcheting mechanism for effecting the tightening of the metal band. These ratcheting mechanisms employ moving mechanical parts, e.g., the ratchet pawl, which eventually become worn so that the pawl slips and loses its grip on the metal band during usage of the tool, thus rendering the tool inoperative for its intended purpose. Such ratchet type tools also have the further disadvantage of being apt to cause the breakage of the metal band during the band tensioning and securing operation. This is so because the ratcheting mechanism, once it has been actuated to set the desired tension in the metal band, cannot be released in any way during the further course of the band applying operation to reduce or ease off on the added tension which develops in the band during the bending back of the free end of the band over the top of the fastening clip to secure it in place thereto, with the result that breakage of the band is likely to occur. In such case, repetition of the band applying operation is required, with attendant loss not only of the ruptured metal band material but loss of the workman's time as well.
The banding tools most commonly used in the past have also had the added disadvantage of limited capability in the angle to which they can bend the free end of the metal band back over the top wall of the fastening clip to secure it in place in the clip in its tensioned condition. These prior tools are able to bend back the free end of the metal band over the top wall of the fastening clip to an angle of only about 45.degree. or so beyond perpendicularity, i.e., beyond a 90.degree. bend. Such a limited angle bending back of the metal band over the fastening clip is insufficient, in most cases, to prevent the bent over free end of the band from being unbent and snapped back into the clip, and thus unloosened, by the pulling force of the tensioned band upon either the release of the metal band from the clamp jaws or other gripping means of the tool or upon the customary severing or cut-off of the excess portion of the bent over free end of the band at a point between the fastening clip and the band gripping means of the tool. When such unloosening of the metal band happens, it then becomes necessary for the workman to start the band tensioning and securing operation all over again, thus wasting work time and, in some instances, wasting the metal band material as well.
In an effort to avoid any such band unloosening occurrence resulting from the above described limited angle of bend over of the free end of the metal band, the workmen using these prior tools have been accustomed to applying finger pressure down on the bent over band end during the release of the band clamp jaws of the tool, or during the cut-off of the excess band material, in order to thereby maintain the bent over band end it its bent over band securing position until it can be subsequently bent down further to lie flat against the top of the fastening clip and then locked in place in the clip by the bending down of the locking lugs on the clip over the bent down end of the band. However, this procedure requires considerable skill and dexterity on the part of the workman to not only hold the heavy and cumbersome banding tool in place but to also simultaneously apply the necessary finger pressure to the bent over band end while at the same time either cutting off the excess band material or opeining the band clamp jaws of the tool to release the band. At best, this procedure constitutes a rather tricky and most difficult time-consuming operation, especially so in the case of a left-handed operator using a tool designed for use primarily by right-handed operators.
Of all the many drawbacks, however, of the prior band tightening and securing tools commonly employed in the past, perhaps the most troublesome and annoying one is their pronounced tendency to cause the clamped or otherwise gripped free end of the metal band to skew out of relative alignment with the tool and its clamp jaws or gripping means during the tensioning of the band by the tool. This skewing action of the metal band in the clamp jaws or gripping means of the tool is caused by the fact that these prior tools have been of the so-called side pull type wherein their band clamp jaws or gripping means are located at one side of the tool and offset from the longitudinal center line thereof so that the pulling forces exerted on the opposite ends of the band, during the band tensioning operation, are not in exact coalignment but instead are at a slight angle to one another. Because of this, and further because the clamp jaws or gripping means of these prior tools have been of the side opening type requiring sidewise slipping or insertion of the free end of the band into the clamp jaws or gripping means of the tool, the skewing action alluded to above results in the band working and slipping sideways out of the open side of the clamp jaws or gripping means during the band tensioning operation and so becoming completely disengaged therefrom and thus unloosened from around the pipeline or other vessel. Repetition of the band clamping and tightening operation is again necessitated, resulting in added lost working time by the band applying workman.